I just built a hop stopper by taking two pieces of 12" SS screen and fold the edges over a coupe times. Put a copper pipe through it and bend the edge down so it sucks up everything. Then slide it into a copper sleeve that has 1/2" threads on one side. I never get hops in my plate chiller...
I made a hop stopper from two 12" SS fry pan splatter screens and folded them around eachother and put a copper pipe coming from the bulkhead right through it
Aeration does hurt if the wort is hot. Ive read that and splashing around whe the wort is over 100 degrees can oxidize the wort because oxygen clings to it easier. (Clings isnt the right word, but i think it was in a palmer book)